Well packer and bridge plug for well bores



Allg- 4, 1953 J. R. BAKER ETAL 2,647,584

WELL FACKER AND BRIDGE PLUG FOR WELL BORES Filed March 11, 1949 2 Sheets-Sheet l .AQTrOQA/Ey Q w l A 5 a a 0 apa, PWM

zsheets-,sne'et 2 IN V EN TORS.

- Aug. 4, 1953 J. R. BAKER ET AL WELL PACKER AND BRIDGE PLUG FOR WELL BoREs Filed March 11, 1949 l .n Zw 4% 4,;

Patentecl 'g". 4, 1953 "UNITED'L, ,sT-Aras PATENT" OFFICE "WELL BACKER YAND BRIDGE PLUG Fon WELL norms .lohn RffBakeryPasadena, and Martin B."Conrad, l Hu'ntingtonPark, Calif.,` assignors tovBaker Oil Tools, :'Inc., v' Vernon, Calif., a corporation of l,

California Application Marc'hlll, 1949,Serial 'No'. 80,836

The present invention relates *to wellf4 packers adapted -to be set in wellfbores, or in-casings liners and similarv conduits located in -wel1 bores. An object of thepresent invention is to provide `an improved `well packer or bridge plug, ywhich is economcalvto manufacture, easily set in al-well bore, and v'capable of withstandingvk substantial pressures when set' in the `well bore.

Another object'of theinventionis to provide an improved locking arrangementfforsecuring packer or well-tool parts in `their-'set conditionin 'a well-bore. More I specically,' the `loclcarrangement'embodies `al lock-'device that enables Athewell Apacker to be-made primarily of readily drillable materials, such as cast iron, magnesium, aluminumy/and the like, and does not "substantially distort ysuchinaterials in preventing'release of the packer from its expanded orset condition.

A further object of the-invention-is to'provi'de a well packer; or fwell tool, embodying slipsvthat are held initially in retracted position in :a simple manner, and vwhich cannot (be shifted vinadvertentlyto expanded position;

This-invention possesses man'yfother 'advantages, andhas` other objects which may bemade morer clearly apparent from a consideration of a form in which it may beem'bodied. This form is shown inthe drawings accompanying and forming part of thepresentspecification. Itwill now'be'described in detailfor thepurpose .of illustrating the Ageneral principles of theinvention;

'but'it is tobe understoodthat such detailed `rdevscription is not to 'be taken in a limiting-sense, since the .scopeof the invention is `bestdefined Fig. 5 is an enlarged fragmentary longitudinal section through the'lock* device of the well tool; Fig. 6 is a cross-section taken lalong the line t-5 on F'iggla, Y

TheI well packer A disclosed in the drawings .includes an elongate central packerbody l0 liaving alowerfguide and abutment i l threaded, or otherwiseattached, to its lower end, and an upper Aabutment |21-movablymounted upon its upper portion. A lower, circumferentially continuous slip sleeve I3 I'r-ests-upon'the lower abutment Il 4and-surroundsf'the upwardly projecting central boss lli of theflatter. This slipsleeve` I3 isprof videdy with an inner yinclined surface I5 `tapering upwardly and outwardly forcooperation with a `companion taperedsurface I6 on a lower frusto- `conical expandery l'lrslidable `along the body lil. Thefexpanderfis preferably made hollow to reduce :its mass, and may have inwardly directed sp'aced'ribs or rannul-irfl' which slide along the 'body member.

A packing assembly I9,l which is preferably of 'natural or synthetic rubber,` encompasses the body and rests `upon the upper end of the lower expander'll. Such end is provided with an annular-step-Ztl-supporting a ow preventing ring "2l having -a 'siibstantially`4` cylindrical external surface 22 'and an Iupward and'outwardly tapering inner surface 23, engaging a corresponding taperedfsurface'M at thetlower portionv of the 4packingjsleeve I9.` Theflow preventing ring 2l isof 4much harder rubber than the rubber of theA packing material I9, `so as'to bridge the clearance vspace 25 betweenv the expander i7 and the"A wall of the casing B in which the packer A is run, fas an incident of ysetting the packer.

In a similar fashion, the upper end of the packing sleeve i9 engages the lower end -of an `upper fru'sto-'conical expander 26,and also coacts with'a hard rubber ow preventing ring 2l disposed around the upper end 'of the packing sleeve and received within anannular recess ESin the upper'expa'nder." The upper expander 2B is-also `slidable along' the upper portionvof the Apacker lbody |0,fand has an upward andinwardiy 'tapering'exi'.erna1 -surface 29 Cooperable with a corn- `panioninternal surface 3B Zon the interior of a circumferentiall'y continuous vupper slip `sleeve '3l whichiengagesthe upper labutment. l2. The inner end` ofthe'fslip'sleeve-BI encompasses a oen- -tering boss A537! depending from the upper abutment.

"It willfbe noted from the drawings that the upperslip sleeve 3l, upper expanderv 2t, upper hard "rubber `bridging ring 21,' and upper portion of theA packingsleeve i9 are'substantially iden- 'tical with the correspondingparts at the lower portion `of the well packern However, the parts are oppositely arranged;` In addition, it is to be notedfthat-'the upper lslip ring 3| is'provided with upwardly'fac'ing wickers -orteeth 33 for ern'- bedding in the wall of the well casing B, to prevent upward movement of the well packer A therewithin. The lower slip sleeve I3 is provided with downwardly facing wickers or teeth 34 for embedding in the casing wall, to prevent downward movement of the well packer therewithin.

The well packer A is set in the well casing B by moving the upper abutment I2 in a downward direction, and the body Ill and its lower abutment II in an upward direction with respect to each other. Since the slip sleeves I3, 3l are initially circumferentially continuous, they are designed to break into segments upon imposition of a predetermined wedging force thereon. Thus, each slip sleeve is of relatively thin section, and has inwardly extending longitudinal ribs that cooperate with an associated expander I'I or 2B. Relative longitudinal movement between each slip sleeve and its associated expander will cause the sleeve to be wedged over the expander and produce a fracturing or breaking of each sleeve at its thin wall sections 38 into separate segments 3l, such segments being movable along the tapered surface of the expander and outwardly into engagement with the well casing B (see Fig. 4). Originally, the slips cannot expand, in view of their circumferential continuity.

The well packer A is run in the well casing to the desired setting point, whereupon the upper abutment I2 is shifted downwardly of the body Ill, to wedge the upper slip sleeve SI over the expander 2B, producing fracture of the sleeve into a plurality of segments 36 and their engagement with the well casing. Inasmuch as these slip segments 36 are wedged between the upper expander 26 and the casing B, they cannot move downwardly to any further extent. The packer body I8 is then shifted upwardly, causing its lower guide and abutment I I to move upwardly, carrying the lower expander I'I and lower slip ring I3 with it as a unit. During this motion, the lower expander I1 is moved toward the upper expander 25, shortening the packing sleeve I9 and expanding it outwardly into firm sealing engagement with the casing B. The hard rubber flow preventing rings k2'I are also deformed outwardly into engagement with the casing b, forming a bridge between the L expanders II, 26 and the casing B, and preventing the relatively softer rubber material of the packing sleeve I9 `from owing through the annular clearance spaces 25 and retaining the packing sleeve in the position where it can perq.

upward movement along the lower expander, accompanied by their radial outward shifting into anchoring engagement with the well casing B, such as disclosed in Fig. 2.

The well packer A is retained with its slips and packing elements in their fully expanded positions by a lock device provided between the movable upper abutment I2 and the body I0. This lock device takes the form of an inherently contractible sleeve 38 of extended length located within an inner recess 39 in the movable abutment I2. The sleeve is provided with upwardly facing annular teeth -40 o n its interior ,G0 segments, of the same general character as the upper slip segments 31, and their longitudinal' engageable with the body I0, which may have a roughened exterior to insure digging in or biting of the ratchet teeth 40 with the body itself. The exterior of the sleeve is provided with upwardly facing annular teeth 4I engageable with companion downwardly facing teeth 42 formed in the movable abutment member.

For economy of manufacture, the internal lock ring teeth 40 may be formed as a buttress thread having upwardly facing transverse locking surfaces, and the roughened surface on the body may be provided by forming a companion shallow buttress thread 43 facing in a downward direction and of the same pitch as the internal ring thread 48. Similarly, the coengaging teeth 4I, 42 on the exterior of the lock ring 38 and the interior of the movable abutment I2 may be formed vas buttress threads of the same pitch.

As stated above, the well packer A is set by relative -downward movement of the upper abutment I2 and upward movement of the body I0. Such relative movements can occur without interference, since .the internal ratchet teeth 40 on the lock sleeve 38 merely ratchet over the corresponding ratchet teeth or roughened surface 43 of the body, without any substantial resistance to its movement. However, any tendency for the body Il] to move in a downward direction within the upper abutment I2, or for the upper abutment to move in an upward direction with respect to the body, is prevented by the locking engagement of the internal teeth 40 of the sleeve 38 with the roughened surface or teeth 43 of the body. In effect, the ring or sleeve 38 operates as a one-way coupling or clutch element, permitting relative upward movement of the body I3, but precluding its relative downward movement. Any tendency for the ring 33 to move downwardly with the body is resisted by wedging of the tapered cam faces 45 of itsteeth 4I with the companion cam faces 46 forming the inclined surfaces of the buttress threads 42 in the movable abutment I2. Such wedging action urges the ring 38 inwardly into the body II'l with a greater force.

It is preferred to make the bridge plug of readily drillable materials, in the event it is desired to remove it from the well casing after it has been set therein. Such materials may be cast iron, aluminum or magnesium, of which .substantially all of the parts, with the exception of the packing assembly, are made. It is preferred to have the slip sleeves I3, 3| made of cast iron, regardless of the use of aluminum or magnesium for the other metallic parts of the well packer. Also, the lock sleeve 38 should preferably be made of some spring-like material, such as cast iron or steel.

In order to prevent bulging of the upper abutment I2 when it is made of comparatively soft, readily drillable material, such as magnesium, the slope of the coengaging cam faces 45, 46 is made much greater to the Vertical, or longitudinal center line of the lock sleeve 38, than the slope of the ratchet tooth faces `4l internally of the lock sleeve. The internal faces 4l' of the inner ratchet teeth make a substantial angle with the generally horizontal faces 48 of the teeth 40, so as to provide a strong tooth shape and allow relatively large forces to be transmitted in a downward direction between the packer body I8 and the lock sleeve IZ. As an example, the acute angle at the edge of such tooth or thread 48 may be about degrees; that is, the sloping face l? of each tooth makes an angle of about l5 degrees @te ther ionfgituamai Center* iine l'of' the lock vsleeve 38.

" If lthe'l coacting cam faces 45,-450nthe movable abutment 'ring l 2 and loek'sleeve `38` possessed `the `same' steep angle a'stheinner'ratchet teeth lily the large downwardforcesion the body Would bemultplied many times bythe' mechanical ad- 'vantage' afforded by the'coactingcarrrfacesl and would tend to bulge or break the movableabut- "1nent"|2; especially if the `latter'wer'amade off magnesiumv or other soft metal. Forjthis reason, the slopingcam` facesrli; dii aref-inclined at a greater angle to the center line of the sleevef38 andy main abutment I2. Asanexample; the

angleof inclination may be lof the order of-al'iouti15A A3i) degrees.` The greaterangle of inclination to the longitudinal center line still -insuresbtlfie wedging of the ring 38 -within the movable'abutment I2 and y-its inward'urging into' firm engagement with the body I il.

- It is to be noted that fwhen'fthefringJ Il2fisfnot under load,v its external cam faces 45 have lateral clearance 48a with the companion-cam faces-7d@ in the abutment ring. This arrangement' permits Downward movement of Similarly; upward movement of thebody lil within the abutment I2 can occur without upwardmovementof the lock sleeve A33 because of the coengaging sleeve;

and abutment teeth faces 5t; 49.

The initial -circumferentially'continuous condition of the slipsleeves` !3,` 3l and the relative V `'stiiness of the rubber `material` of the packing "assembly IS will cause the partsto' remainin their retracted positions during lowering ofthe tool in the well'bore, as disclosed in Fig: la. As assurance against downward movement of the movable abutment I2, or relative upward movement 'of' the body It), during lowering.,y of the well packer A in the well casing B, a shear nin or screw 5l may extend between the upperabntment I2 and the body ill. This screwtl'sv dis rupted when the wellpacker A is to-be set.

The well packer may beset by Vany means which is capable of imposing a downward forceL on the upperv abutment I2 and anupwardforce on'the 7 body I6.

A setting tool C forperforming' this function is illustrated in'ligs. 1" and la.' This 'setting tool enables the entire apparatus to be lowered in thewell casing on aiwire line D.

' yThe 'setting tool C includes'a cylinder 55 Lhavn ing upper and 'lower heads .56,51 threaded into the opposite ends of a cylinder'sleeve 53. The upper head is threaded ontoa cable head@ se;

cured to the 'wire "line D inr a' known 'manner f "Also'threaded intothe cable'hea'd is agun' barrel $0 containing a 'blank cartridge 6I connected `electrically to the conductive core B2 of the wire "line. 'This cartridge 6i, when red; ignites'the 'upper end of a combustible charge 63, such as a railway flare,` disposed Vwithin a' combustion chamber 6d in theupper headedl Thecomunbustible charge generates gases under `pressure within the cylinder 55,' forcing a" piston E5 'downwardlywithin the oylindenor reactively eleVat-l` ing the cylinder'itself.

'f The piston is secured to a depending piston "rod 65 'extending through the cylinder vhead 5l and intoan elongate tubularma'ndrel tl threaded into the-1 lower head 51.

The' lower end' of thisman" drel is threadedly-secured-to acouplingal'sleeve Y `lA`681"` thatf'has 'an`adapter" 69 isecured to y ityL into "whichlthe upper end of a'A disruptableltension stud I isvthreaded. The lowerv end off this tension stud is threaded into theupper fend ofthe-pacler body I0. The tension stud has a'vreduceclv diametermedial'po-rtion It to-insure-.apul1ing"apart of lthest'udfat this pointgwhen the'ultimate load capacit-y of the stud in tension is: exceeded.

lillrefpiston rod-66 has a cross-piecefl mounted in'-its-lcwerslot13,l 'which extends-fin* opposite di- -'^1rections"-from the rod through aligned `elongate lslots-114' in the tubular .mandrel 6l. TheV crossv piece extends beyond these slots andinto aligned slot'sfil in a's'etting ring IIL-on which the upper e end of a setting sleeve il` islthreadedlyl secured. `-This setting' Sleeve extends downwardly?r alone i the mandrel and yhas an adapter'rinell secured to `-its=flower end,y to which' an.y adapterisleeve.; l@

isf attached, as byuse of welding material td.

"The lower 'end of this adapter sleeveA bearsnpon i a'shoulder SI ofthe movable abutmentimenb ber I2.

" Leakage-from` and into lthe cylinder-55 ispre- Yvented by suitable sealrings 132; whercas-leakage along the l'piston 65 is prevented bythe pis- -tonrings S3.

The well vpacker Apwithits vparts in retracted -posi-tion, issecured to the' setting tool C. and this combination is `1o\.'fered on `the wire line D'within `the Well-casing" B to' thedesired setting point. "i When such'point is reachedpthe-blanlc cartridge 'j I- is -red electrically to ignitethe-upper end of 1 the powder or combustible charge 63. lBurning of thisf'charee generates ay gasl capable? of :exerting a downward force on the vpistonA and piston rod tt, shifting athenr downwardly 'within; the `cylinder55, and-also l'rlfif'Jv-ing'the crossepiece '12; setting ringe l, setting sleeve ll', adapter ."ring :'lland adapter sleeve lil in a downward direction. .u Such downward movement nrst disrupts the shearfpin' 5I and shiftst'ne upper abutment I2 downwardly,

as permitted by ratcheting of the lockrsleeve 38 downwardlylover thebody lll, -wedgingl the .upper slip sleeve 3I loverthe.upper.expanderfj. `his wedging actionfbreaks the slip sleeve 3l. intcsegments3l' and enables. suclixsegments tofbe expanded outwardly intoiwedeing engagement with l the-'wallv ofuthe wellcasingT B.

f/.Af-ter such wedging'engagement has occurred, the pistonipiston rod crossfpiece l2; setting ring-fit,y setting sleeve ll, adapterzring id-adapter 'l sleeve` l9yupper abutn'lentv l2 and slips 3i cannot move downwardly to anyrfurther extent.` Further increase` in the-gaslprcssure in the ycylinder :55,- as aN-result of continuedcombustion' of the charge G3;=then causes the cylinder 55' t'otmove upwardly; whichexerts'an `upwardy pull on 4the tubular mandrell 6l; tension stud ll-paclierbody -I'-and the body abutment il; in order to foresho'rtenthe-packingsleeve' mand expand it outwardly against the wellcasine Bras welly as deform' the flow preventing `rings 2l', 2 outwardly against the wellcasing.

Continued'upward movement ofthe packer body I0 thenwedges the lower slip'sleeve I3 over 'the `lower expander' Il,` breaking the sleeve' into a plurality of segments, which are expanded'outwardly against thecasing B. `Asthe pressure in Vsively greater-upward force isimposed on the cylinder,tubular mandrel B'ltension stud-lil and body Ito firmly-and; securely anchor the well the cylinder 55 continues to increase,a'prog1es- 1 packer A in packed-orf -condition within-the well fcasings'x When-the'tensilee vrstrength ofletheestucl i is exceeded, it will be pulled apart at its reduced diameter portion 'l l, automatically releasing the setting tool C from the anchored bridge plug A. The setting tool may now be removed from the well casing by means of the wire line D (see Fig 2).

Following release of the setting tool C from the well packer A, the latter will remain locked in its packed-off condition. Any tendency for the packer to move upwardly will be resisted by the upper slips 3|, since such upward force is trans-l mitted from the lower guide and abutment Il, through the lower slips I3, lower expander Il, packing sleeve I9, upper expander 26 and upper slips 3l to the well casing B. Any tendency for the well packer body l0 to move downwardly is resisted by the lower slips I3. This downward movement is transmitted from the body I0 through the lock sleeve 38 to the upper abutment l2, and from the upper abutment through the upper slips 3|, upper expander 26, packing sleeve i9, lower expander il and lower slips i3 to the well casing B.

It is accordingly apparent that a comparatively inexpensive well tool has been devised that can function as a well packer or anchor in a well bore. The parts are held in their initial retracted positions by themselves, and are readily expanded against the well casing when desired. After such expansion, they are retained in that condition because all of the parts are locked and wedged to one another and cannot be released. The locking arrangement isk such as to enable the parts to be made of readily drillable materials, without bulging or becoming released inadvertently.

The inventors claim:

1. In a well tool: a body; an expander on said body; and a circumferentially continuous, frangible slip member engageable with said expander, said expander being movable longitudinally with respect to said slip member to exert a lateral force on said slip member to break said slip member into segments.

2. In a well tool: a body; an expander on said body having an external tapered surface; and a circumferentiaily continuous, frangible slip member having a tapered internal surface engageable with said external expander surface, said slip member being capable of being broken into segments by said expander upon relative wedging of said expander into said slip member.`

3. In a well tool: a body; an expander on said body having an external tapered surface; and a circumferentially continuous, frangible slip member having circumferentially spaced ribs therewithin, said ribs being provided with tapered surfaces engageable with said external expander surface, said slip member being capable of being broken into segments by said expander upon relative wedging of `Said expander into said slip member, the regions where said member is broken lying between said ribs.

4. In a well tool: a body; an upper expander on said body having an external tapered surface inclined upwardly and inwardly; an upper circumferentially continuous, frangible slip member having a tapered internal surface engageable with said external surface; a lower expander on said body having an external tapered surface inclined downwardly and inwardly; a lower circumferentially continuous, frangible slip member having a tapered internal surface engageable with said lower expander external surface; each of said slip members being capable of being broken into `Segments by its companion expander upon rela-` tive wedging of said companion expander into its slip member; an abutment on said body engageable with one of said slip members; and another abutment slidable along said body and engageable with the other of said slip members; said abutments having bosses devoid of lateral projections extending within said slip members for centering said slip members with respect to said body.

5. In a well tool: a body; an expander on said body; slip means operatively associated with said expander; an abutment engageable with said slip means and slidable along said body in one direction to shift said slip means along said expander and outwardly into anchoring engagement with a well conduit; and lock means for preventing movement of said abutment relative to said body in the other direction, said lock means comprising a split sleeve having internal teeth engageable with said body, said sleeve also having external cam teeth engageable with companion internal cam teeth on said abutment to urge said sleeve internal teeth laterally inward into engagement with said body.

6. In a well tool: a body member; an expander on said body member; slip means operatively associated with said expander; an abutment member engageable with said slip means and slidable along said body member in one direction to shift said slip means along said expander and outwardly into anchoring engagement with a well conduit; and lock means for preventing movement of said abutment member along said body member in the other direction, said lock means comprising a split sleeve having inner and outer surfaces, ratchet teeth on one of said surfaces engageable with one of said members, and cam teeth on the other of said surfaces engageable with companion cam teeth on the other of said members to urge said ratchet teeth into engagement with said one of said members.

7. In a well tool: a body; normally retracted means on said body; an abutment engageable with said normally retracted means and slidable along said body in one direction to shift said normally retracted means outwardy; and lock means for preventing movement of said abutment along said body in the other direction, said lock means comprising a split, inherently contractible sleeve having internal teeth engageable with said body, said sleeve also having external cam teeth engageable with internal cam teeth in said abutment to urge said sleeve internal teeth into engagement with said body.

8. In a well tool: a body member; normally retracted means on said body member; an abutment member engageable with said normally retracted means and slidable along said body member in one direction to shift said normally retracted means outwardly; and lock means for preventing movement of said abutment member along said body member in the other direction, said lock means comprising a split sleeve having inner and outer surfaces, ratchet teeth on one of said surfaces engageable with one of said members, and longitudinally spaced cam teeth on the other of said surfaces engageable with companion longitudinally spaced cam teeth on the other of said members to urge said ratchet teeth into engagement with said one of said members.

9. In a well tool: a body member; normally retracted means on said body member; an abutment member engageable with said normally retracted means and slidable along said body member in one direction to shift said normally retracted means outwardly; and lock means for preventing movement of said abutment member along said body member in the other direction, said lock means comprising a split sleeve having inner and outer surfaces, ratchet teeth on one of said surfaces engageable with one of said members, and longitudinally spaced cam teeth on the other of said surfaces engageable with cornpanion longitudinally spaced cam teeth on the other of said members to urge said ratchet teeth into engagement with said one of said members, the converging cam faces of said cam teeth making a substantially greater angle to the axis of the body member than the back faces of said ratchet teeth.

10. In a Well tool: a body member; normally retracted means on said body member; an abutment member disposed above and engageable with said normally retracted means and slidable downwardly along said body member to shift said normally retracted means outwardly; and lock means for preventinT relative upward. movement of said abutment member along said body member, said lock means comprising a split inherently contractible sleeve having inner and outer surfaces, ratchet teeth on one of said surfaces engageable with one of said members, and cam teeth on the other of said surfaces engageable with companion cam teeth on the other of said members to urge said ratchet teeth into engagement with said one of said members.

11. In a well tool: a body member; normally retracted means on said body member; an abutment member engageable with said normally retracted means and movable along said body member in one direction to shift said normally retracted means outwardly; and lock means for preventing relative movement of said abutment member along said body member in the other direction, said lock means comprising a split sleeve having inner and outer surfaces, one of said` surfaces having gripping engagement with one of said members, and longitudinally spaced cam teeth on the other of said surfaces engageable with companion longitudinally spaced cam teeth on the other of said members to urge said one of said surfaces into engagement with said one of said members.

12. In a well tool: a body member; normally retracted means on said body member; an abutment member disposed above and engageable with said normally retracted means and slidable downwardly along said body member to shift said normally retracted means outwardly; and lock means for preventing relative upward movement of said abutment member along said body member, said lock means comprising a split sleeve having an inner surface capable of gripping said body member, said split sleeve having longitudinally spaced cam teeth on its outer surface engageable with companion longitudinally spaced cam teeth on said abutment member to urge said inner surface into engagement with said body member.

13. In a well tool: a body; normally retracted means on said body; an abutment engageable with said normally retracted means and slidable along said body in one direction to shift said normally retracted means outwardly; and lock means for preventing movement of said abutment along said body in the other direction, Said lock means comprising a split sleeve having internal teeth engageable with said body, said sleeve also having an external helical thread meshing with a companion internal helical thread in said abutment to urge said sleeve inwardly into engagement with said body.

14. In a well tool: a body; normally retracted means on said body; an abutment engageable with said normally retracted means and slidable along said body in one direction to shift said normally retracted means outwardly; and lock means for preventing movement of said abutment along said body in the other direction, said lock means comprising a split sleeve having internal teeth engageable with said body, said sleeve also having an external buttress thread meshing with a companion internal buttress thread in said abutment.

15. In a well tool: a body; an expander on said body; slip means operatively associated with said expander; an abutment engageable with said slip means and slidable along said body in one direction to shift said slip means along said expander and outwardly into anchoring engagement with a well conduit; and lock means for preventing movement of said abutment relative to said body in the other direction, said lock means comprising a split sleeve having internal teeth engageable with said body, said sleeve having an external buttress cam thread meshing with a companion buttress cam thread in said abutment.

JOHN R. BAKER. MARTIN B. CONRAD.

References Cited in the file 0f this patent UNITED STATES PATENTS Number Name Date 654,875 Cook July 31, 1900 2,021,223 Church Nov. 19, 1935 2,153,035 Burt Apr. 4, 1939 2,204,648 Baker June 18, 1940 2,241,532? Barnes May 13, 1941 2,467,801 Baker Apr. 19, 1949 2,589,506 Morrisett Mar. 18, 1952 

